1. Field of the Invention
The invention concerns a dissipator for electronic components, the electronic components being intended for the functioning of a rotary electrical machine, the machine comprising a rear bearing, the dissipator comprising a top face and a bottom face including fins.
The present invention applies to any type of polyphase rotary electrical machine, synchronous or asynchronous, such as alternators or alternator starters, and also whether it is a case of electrical machines for motor vehicles and driven for example by belt, with cooling by air, liquid or any other solution that can be envisaged.
2. Description of the Related Art
In a motor vehicle comprising a thermal engine and a rotary electrical machine such as an alternator starter, such an electrical machine comprises for example, non-limitatively:
a rotor comprising a field winding into which an excitation current is brought; and
a stator comprising a polyphase winding.
The alternator starter functions in motor mode or in generator mode. It is a so-called reversible machine.
In generator or alternator mode, the machine converts a rotation movement of the rotor driven by the thermal engine of the vehicle into an electric current induced in the phases of the stator. In this case, a bridge rectifier connected to the phases of the stator rectifies the sinusoidal induced current into a DC current in order to supply consumers on the vehicle such as a battery.
On the other hand, in motor mode, the electric machine serves as an electric motor for rotating, via the shaft of the rotor, the thermal engine of the vehicle. It converts electrical energy into mechanical energy. In this case, an inverter converts a DC current coming from the battery into an alternating current for supplying the phases of the stator in order to rotate the rotor.
Control signals are used to determine the operating mode of the rotary electrical machine (motor mode or generator mode).
In the document DE 102004007395 A1, the use is known of an external peripheral band, the band comprising internal partitions including:
signal interconnection tracks for the transmission/reception of signals to the electronic components from the bridge rectifier/inverter; and
power interconnection tracks for connecting the electronic components to the battery so as to supply them;
all the tracks being superimposed on one another and being overmolded. The band is positioned on the rear bearing of the machine. In addition, a dissipator is positioned above the band.
One of the problems of such a solution is that there exists solely an air flow blown by the fan of the rotary electrical machine for cooling in particular the machine and the electronic components, the air flow being an axial air flow. This single air flow may be insufficient to allow effective cooling.